Apparatus for neutralizing fatty oils



Jan. 9, 1968 L. o. BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS Original Filed Oct. 22. 1962 10Sheets-Sheet 1 LARS O. BERGMAN BY M, LL), {r

ATTORNEYS INVENT OR Jan. 9, 1968 L. o. BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS INVENTOR L-ARS o. BERGMAN BY M FMATTORNEYS Jan. 9, 1968 L. o. BERGMAN 3,362,794

' APPARATUS FOR NEUTRALIZ ING FATTY OILS Original Filed Oct. 22. 1962 10Sheets-Sheet 5 INVENT OR nu 1/ /77777 LARS o. BERGMAN & ATTORNEYS Jan.9, 1968 o. BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS Original Filed Oct. 22. 1962 10Sheets-Sheet 4 ms h INVENTOR LARS 0. BERGMAN WWW m BY p ATTORNEYS Jan.9, 1968- Original Filed Oct. 22, 1962 Vll L. O. BERGMAN APPARATUS FORNEUTRALI'ZING FATTY OILS 10 Sheets-Sheet 5 c;- as

F/aa INVENTOR 9| 94 93 LAR'S O. BERGMAN BY "a W ATTORNEYS Jan. 9, 1968L. o. BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS I Original Filed Oct. 22. 1962 10Sheets-Sheet 6 FIG. 7

INVENTOR LARS O. BERGM AN WWTL, m

ATTORNEYS Jan. 9, 1968 L. o. BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS Original Filed Oct. 22. 1962 v 10Sheds-Sheet 7 FIG. 8

INVENTOR LARS O. BERGMAN BY @M FM ATTORNEYS v Jan. 9, 1968 L. o. BERGMAN3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS Original Filed Oct. 22. 1962 10Sheets-Sheet 8 I INVENTOR LARS O. BERGMAN ATTORNEYS Jan. 9, 1968 L. o.BERGMAN 3,362,794

APPARATUS FOR NEUTRALIZING FATTY OILS Original Filed Oct. 22. 1962 l0Sheets-Sheet 9 v INVENTOR LARS' 0.;BERGMAN BY wM, LA

Jan. 9, 1968 1.. o. BERGMAN APPARATUS FOR NEUTRALIZING FATTY OILS 10Sheets-Sheet 1 0 Originl Filed Oct. 22, 1962 NNHQK INVENT OR LARS o.BERGMAN ATTORNEYS United States Patent 3,362,794 APPARATUS FORNEUTRALIZING FATTY OILS Lars 0. Bergman, Malmo, Sweden, assignor toAktiebolaget Aritmos, Goteborg, Sweden, a Swedish joint-stock companyOriginal application Oct. 22, 1962, Ser. No. 232,146, now Patent No.3,226,047, dated Dec. 28, 1965. Divided and this application Dec. 27,1965, Ser. No. 516,242

10 Claims. (11. 23-285) ABSTRACT OF THE DISCLOSURE Apparatus forneutralizing fatty oils by bubbling the fat up through a vertical columnof alkaline aqueous solution having throughout its height a horizontalcross sectional area of at least 1 sq. m., comprises a stationarystanding tank, a perforated horizontal partition in said tank dividingthe interior thereof in an upper compartment of a height of at least 2In. adapted to hold said vertical column of alkaline aqueous solution,and a lower compartment with an inlet for a feed of oil to beneutralized, means including said perforated horizontal partition andforming a plurality of separate outlets disposed in a uniformdistribution over the horizontal cross sectional area of said uppercompartment at the base thereof for distributing the fat feed from saidlower compart ment in separate streams up into the column of alkalineaqueous solution in said upper compartment through said separateoutlets, means comprising vertical partitions dividing the interior ofsaid upper compartment at a lower part extending from a horizontal planeclose to said outlets and amounting to at least 20 cm. of the height ofsaid upper compartment into vertical cells of an individual crosssectional area of about 5 to 50 sq. cm. for suppressing turbulent motionof the alkaline aqueous solution in said upper compartment under theinfluence of the bubbling up of the fat therethrough, and means formingbetween said upper and lower compartments a line of communication whichin the operation of the neutralizer keeps filled with alkaline aqueoussolution to enable the oil fed to said lower compartment to spreadtherein into a layer of variable thickness between said perforatedhorizontal partition and a bottom layer of alkaline aqueous solution insaid lower compartment. A basic arrangement and a number of modifiedforms are disclosed.

This application is a division of copending application Ser. No.232,146, filed Oct. 22, 1962 (now US. Patent No. 3,226,047), which is acontinuation-in-part of my application Ser. No. 841,058, now abandoned,and Ser. No. 75,230, a continuation-impart of Ser. No. 841,056, nowabandoned. Ser. No. 841,056 and Ser. No. 841,058 (both now abandoned)were filed on Sept. 21, 1959. Ser. No. 75,230 (now abandoned) was filedon Dec. 12, 1960.

This invention relates to a plant for industrial refining of vegetableand animal fatty oils and other fats for edible purposes. The processaspect per se has been disclosed and claimed in the aforesaid parentapplication. Ser. No. 232,146.

Most crude vegetable and animal fatty oils and other fats, whetherobtained by pressing, solvent extraction or rendering, are given apreliminary cleaning and clarification treatment. When required foredible purposes they are nearly always given a series of furthertreatments, which comprises a pre-treatment consisting of or includingdegumming, usually by means of acid, and then neutralization by means ofcaustic soda solution or other alkaline aqueous solution, bleaching,usually in the form 7O filtering of 3,362,794 Patented Jan. 9, 1968 ofadsorption bleaching, and deodorization. These treatments are all knownin many variations. Heating to about or above C. in or prior todegumming and neutralization is known to be detrimental to all such fatsas are used industrially for the manufacture of such edible products asmargarine. In degumming by acid it has ben proposed to give preferenceto phosphoric acid (H PO over other strong mineral acids such assulphuric acid and hydrochloric acid.

In this application the term refining is applied, as is usual in theUnited States of America, to the operations of pre-treatment andneutralization and thus not, as is usual in many other countries, to thecomplete series of treatments, including bleaching and deodorization, tomake the fat suitable for edible use. Consequently, the chief object ofthis invention is to devise new apparatus for contacting fat withcaustic soda solution or other alkaline aqueous solution by bubbling thefat up through a column of such solution for converting free fatty acidsin the fat into soaps dissolving in the aqueous solution, therebyforming a by-product known as soapstock.

One economically important problem in connection with the refining offats for edible purposes is to keep the refining loss of neutral fat,which cannot be entirely avoided, as low as possible. As is well known,emulsion formation and over-saponification are the chief sources of lossof neutral fat with th by-product, the soapstock, in wet neutralizationof fats by means of alkali. One object of my invention is to eliminateor minimize the loss of neutral fat with the by-product, the soapstock,of the neutralization operation.

Another object of my invention is to eliminate the need of theconventionally required relatively costly washing of the neutralized fatwith hot water and/or dilute aqueous solutions of suitable chemicalssuch as common salt and soda ash for a substantially complete removal ofsoap and alkali residues in the neutralized fat after the separationthereof from the spent lye (the soapstock). The elimination of washingof the neutralized fat automatically eliminates the otherwiseunavoidable loss of some neutral fat with used washing media.

The removal of soap and alkali residues in fat after lye neutralizationof the fat and separation of the neutralized fat from the used lye (thesoapstock) is so closely connected with the operation of neutralizingthe fat that this removal practically can be considered a finishing stepof this operation. A still further object of my invention is to carryout this finishing step of the refining of the fat by a comparativelycheap treatment of the fat, in combination with vacuum drying of thefat, with an aqueous solution of an acid selected from the large groupof acids which in accordance with common chemical knowledge have adissociation constant higher than that of the fatty acids of the fat,and which with such alkali as is used in the neutralization operation ofthe fat refining process forms a salt that in soluble in water andinsoluble in fat, so that the selected acid in accordance with the wellknown mechanism splits the soap residue in the fat into free fatty acidsdissolving in the fat, and alkali, and so that the salt which the acidforms with the alkali in the fat is precipitated in solid form in thefat by the vacuum drying thereof and can be removed by filtering. Foralready known reasons, preference is given to citric acid over otheracids which, like citric acid, belong to the above-defined large groupof acids. A still further object of my invention is to combine thistreatment of the neutralized fat for removing soap and alkali residuestherein with the conventional adsorption bleaching, if any, and with theconventional vacuum drying and the refined fat prior to thedeodorization which is the last treatment in the series of treatments 3which the fat must be given to make it suitable for the manufacture ofedible products such as margarine.

When ready for the last treatment, the deodorization, the fat must befree from soap residue. A small free fatty acid content is much moretolerable than a small soap residue in the fat when ready for themanufacture of edible products such as margaine. Even traces of soap inthe fat can unfavorably affect the taste or flavor of the fat and theedible products produced therefrom. In known and most applied practice,the conventionally required adsorption bleaching is relied on forcompleting the removal of the soap residue in the neutralized fat, forwhich purpose the bleaching earth or other adsorption bleaching agentmust be used in a greater amount than otherwise would be necessary. Theelimination by my in vention of the need of the conventionally requiredadsorption bleaching of the neutralized fat, or the reduction of theamount of bleaching agent required for the bleaching, if any,eliminates, or reduces, such loss of neutral fat as is caused byretention of fat in any used adsorption bleaching agent. It is true thatfat in spent bleaching earth as well as in spent filter aid can berecovered, but such recovering is costly and invariably yields fat ofpoor quality, so that most refineries discard spent bleaching earth andspent filter aid without treatment.

Because the boiling point of the free fatty acids is lower than that ofthe fat, the deodorization, which is a high temperature treatment, mayserve also the purpose of lowering a somewhat too large content of freefatty acids in the fat so as to render the fat satisfactory for edibleuse. Therefore, as is well known, the neutralization operation,including the abovementioned vacuum drying, need not necessarily becarried to a complete removal of the free fatty acids in the fat. It isknown that in some carefully prepared fats (such as lard and certainlow-temperature produced vegetable oils from selected fruit and seed) alowering of the content of free fatty acids to a small percentage, about0.5 percent or less, depending on the nature of the fat and the freefatty acids therein, may be satisfactory, However, in al such fats asare used industrially for the manufacture of such edible products asmargarine and require refining, a thorough elimination of free fattyacids is necessary or desirable and also helps to reduce the cost ofremoving other undesirable constituents.

Both from the point of view of cost and of efficiency, caustic soda isnearly the only alkali used in industrial neutralization of fats foredible purposes. Though not intended to alter this practice, myinvention is not limited to using caustic soda solution for theneutralization operation. The new continuous method of my invention forcarrying out the neutralization operation is applicable also with otheralkaline aqueous solutions. For example, caustic potash solution may beused where desired for the reason that the potassium soaps are morereadily soluble than the sodium soaps. Also, alkali carbonate andammonium hydroxide solutions may be used. The new continuous method ofmy invention for carrying out wet neutralization of fats (also such ablend of a fat and a solvent therefor as is called a miscella) by meansof alkali can be used not only for thorough neutralization but also forpart-neutralization, if so desired for one reason or the other.

The extent to which a fat should be decolored is a question of itsfuture use. The invention is concerned chiefly with the refining of fatsfor the manufacture of such edible products as margarine which usuallyhave to be artificially colored with reddish to yellowish coloringmatter, often of carotene character. For this reason there is, as arule, no need of a thorough elimination of coloring matter of thischaracter by the decolorizing effect of the refining process of myinvention in any form thereof including my new semi-continuous method ofcarrying out the pre-treatment of the fat with orthophosphoric acid andmy new continuous method of carrying out the alkali neutralization ofthe fat by bubbling it up through a caustic solution. The refiningprocess of my invention in such a form thereof has proved to be highlyselective in its effect of removing coloring matter in the fat andremoves undesirable greenish coloring matter, which chiefly is ofchlorophyll character, much more completely than reddish to yellowishcoloring matter which chiefly is of carotene character and does notinterfere with the aim of the artificial color which the edible productsare to be given.

All such crude fats as are taken into refineries for processing containmoisture. In already proposed degumming by phosphoric acid, the moisturein the fat has been found to make filtering of the acid-treated fat forthe removal of formed sludge prior to following lye neutralization ofthe fat slow and difficult. It has been suggested and tried, thoughwithout much success, to overcome this difficulty by performing thetreatment of the fat with phosphoric acid in the presence of anabsorbent substance such as cellulose. Phosphoric acid is miscible withWater in all proportions, and the presence of an absorbent substancesuch as cellulose in a fat at a pretreatment thereof with phosphoricacid does not inhibit dilution of the phosphoric acid by water in thefat. The use of an absorbent substance such as cellulose involves lossof some neutral fat with the spent absorbent substance.

The basic point of novelty of my new semi-continuous method of carryingout the pre-treatment of the fat with phosphoric acid (H PO prior to thelye neutralization of the fat by my new continuous method of bubblingthe fat up through a lye column as described below, consists incontacting the phosphoric acid with the fat by stirring at an elevatedtemperature in the range about 60 to about 90 (1., preferably in therange about to about C., in substantially complete absence of Water andatmospheric oxygen for a period of at least 5 minutes and preferably inthe range about 15 to about 30 minutes, since the desirable reactionswhich at said elevated temperature and substantially complete absence ofwater and atmospheric oxygen take place between the phosphoric acid andcoloring matter, phosphatides and other undesirable natural constituentsor decomposition products such as oxidation products held in solution orcolloidal suspension in the fat, have been found to be slow. Therequired degree of absence of water and atmospheric oxygen at thecontacting of the phosphoric acid with the fat is such as is practicallyobtainable only by vacuum drying the fat by evacuation to an absolutepressure below 60 and preferably about 20 mm. of mercury and holding thefat under this vacuum in the reaction zone. For minimizing the additionof water to the fat together with the phosphoric acid, the latter shouldbe of a high concentration, preferably as high as 85 percent by weight,at the addition thereof to the fat, and dilution of the added phosphoricacid by water in the fat should be avoided by thoroughly removing thewater in the fat by the vacuum drying thereof before the phosphoric acidis added to the fat. Since the phosphoric acid is used in a small amountalready, a small amount of Water in the fat is sufiicient for aconsiderable dilution of the phosphoric acid. When using an 85%phosphoric acid, the required amount thereof varies in the range of0.025 to 0.6 or in exceptional cases up to about 1 percent by weight ofthe fat with the content of such undesirable constituents and impuritiesin the fat as are removable by the above-described degumming byphosphoric acid. With a given fat to be refined, the suitable amount ofphosphoric acid to be used can be determined or estimated by theguidance of conventionally required analyses of the fat and laboratorytests for refining and decoloring efficiency. Filtration of the fat fora thorough removal of formed precipitates or sludge prior to theneutralization operation should be performed in thephosphoric-acid-treated and vacuum-dried state of the fat withoutadmittance of air. Under these conditions the filtration can be carriedout without difliculties through a filter given a pre-coat of a suitablefilter aid such as kieselguhr. This filtration also decreases the amountof residual phosphoric acid in the degummed fat. A clarification of thephosphoric-acid-treated fat by centrifugation prior to the filtrationcan be performed for speeding up the filtration and for reducing therequired amount of filter aid and thereby also the loss of neutral fatwith spent filter aid.

In connection with my new continuous method of carrying outneutralization of degummed fats by bubbling the fat up through a columnof caustic soda solution or other alkaline aqueous solution capable ofbeing used for industrial alkali wet neutralization of fats, I use inthis specification for convenience the term lye, unless otherwisespecified. to cover any such alkaline aqueous solution. Lye-treatment offats for neutralization purposes is nearly always performed at anelevated temperature in the range about 60 to about 90 C., and thisapplies also to the continuous neutralization method of my invention.

For carrying out neutralization of degummed fats by my new continuousmethod of bubbling the fat up through a column of lye on an industrialscale, this liquid column must have throughout its height a horizontalcross sectional area of at least about 1 sq. m. and preferably not lessthan about 2 sq. m., so that the apparatus, called the neutralizer,required for practising this method must comprise a large stationaryreceptacle properly describable as a standing tank for holding thisliquid column. The feed of the fat to the lye column at the base thereofmust be subdivided into thousands, preferably about ten thousands persq. m. of the horizontal cross-sectional area of the lye column,substantially equal separate streams of such a regulated rate of flowand moderate initial velocity that they on flowing into the lye columnare caused by their buoyancy in the lye to rise therein likesubstantially vertically projecting footstalks and to keep on breakingup at their tops into drops of substantially equal size in the range 0.3to 3 mm., preferably about 1.5 mm., which drops ascend in interspacedrelation substantially their shortest ways substantially vertically upthrough the lye column, provided that this desired course of thebubbling up of the fat through the lye column is not spoiled byturbulent or like motion of the lye. On flowing into the lye column andbreaking up into separate drops, the large number of fat streams have amarked tendency to bring about turbulent motion of the lye. If suchturbulent motion of the lye is not inhibited or suppressed to asuflicient extent, it disturbs the fat drop formation by impartingirregular motions to the fat streams in the lye and causing them tobreak up irregularly and thereby to a large extent into drops of widelyvarying sizes and to a considerable extent into rather small drops whichpromote both emulsion formaation and over-saponification and produceundesirable variations during the residence time of the individual dropsin the lye before they collect on top of the lye column and form thereona layer of neutralized fat which can be continuously removed.

In order to achieve the desired breaking up of the large number ofseparate fat streams soon after their entrance into the lye column,separate drops of sub stantially equal size within the above-statedrange and preferably about 1.5 mm. and thereby sufiiciently large fornot promoting emulsion formation or over-saponification, I have found itnecessary to hold the lye dampened against turbulence by means ofturbulence dampeners consisting of vertical partitions subdividing thelarge total horizontal cross-sectional area of the lye column on atleast part of the height of the lye column from near the base thereof(namely at least in a lower region of the lye column where the separatefat streams flow like substantially vertically projecting footstalks upin the lye and break up into separate drops) into vertical cells of ahorizontal cross sectional area in the range about 5 to about 50 sq. cm.These cells should of course be open at their upper ends and preferablyalso at their lower ends. The greater the height and the smaller thehorizontal cross-sectional area of the cells, the greater theirturbulence dampening effect in the lye column. The minimum turbulencedampening effect required for the purpose of my invention is thegreater, the larger the number of separate fat streams brought to flowinto the lye column per unit of the horizontal cross-sectional area ofthe lye column. When this number is about ten thousands per sq. m. ofthe horizontal cross-sectional area of the lye column and when using apreferred arrangement of the turbulence dampening vertical partitions sothat they form between them vertical cells of square cross-section, alength of about 4 cm. of the side of this square and a height of about20 cm. of the vertical partitions have been found satisfactory also fromthe point of view that it is not desirable to reduce the totalhorizontal cross-sectional area of the lye column by the totalhorizontal cross-sectional area of the vertical partitions on a largerpart of the height of the lye column than necessary for the purpose ofmy invention.

Also such turbulence or convection motion of the lye as may be caused bysignificant differences in temperature between ditferent points of thelye column has a disturbing effect on the desired course of the bubblingup of the fat through the lye column and should be avoided by keepingthe lye at substantially uniform temperature throughout the lye column.This may require heat insulation of the outer walls of the neutralizersince it is against my invention to agitate the lye by stirring orotherwise during the bubbling up of the fat through the lye column.

My invention also contemplates as preferred method and preferred meansfor effecting the subsdivision of the feed of the fat to the lye columninto the thousands of substantially equal separate streams, forrealizing a desirable fairly uniform distribution of the outlets throughwhich these streams enter the lye column at the base thereof oversubstantially the entire horizontal cross sectional area of the lyecolumn, and for regulating the rate of flow and the initial velocity ofthese streams as required for achieving the desired course of thebubbling up of the fat through the lye column under the condition ofsubstantial non-turbulence therein. The preferred means for thesepurposes comprise a division of the tank of the neutralizer by apreforated substantially horizontal partition or false bottom into anupper compartment containing the lye column through which the fat isbubbled up, and a lower compartment to which the degummed fat is fed.The subdivision of the feed of the fat into the thousands ofsubstantially equal separate streams is effected preferably bydistributors disposed in the upper compartment on or close to thehorizontal false bottom and provided with spaced lateral openingsforming the separate outlets for said stream. The fat is caused to flowthrough the holes in the false bottom up into said distributors from afat layer which the fat fed to the lower compartment forms between thefalse bottom and a bottom layer of lye which communicates with the lyecolumn in the upper compartment through a passage which by-passes saidfat layer and keeps filled with lye. Uniform regulation of the rate offlow of the thousands of separate fat streams entering the lye columnthrough the distributor outlets is achieved by the height of the fatlayer in the lower compartment being regulated by the regulation of thefeed of the fat thereto. By this method it has proved easy to cause thethousands of separate fat streams to flow into the lye column underlittle, if any, other motive force than their buoyancy in the lye andnot only at such a rate of flow but also at such a moderate initialvelocity that the streams, under the condition of substantialnon-turbulence of the lye through which the fat is bubbled up, soonafter their entrance into the lye column break up almost quantitativelyinto substantially equal drops of the desired size. In this connection Iwish to say that it may happen and is acceptable and not outside thescope of my invention that the separate fat streams do not break upfully quantitatively into substantially equal drops of the desired sizebut to some small amount also into rather small, even minute, drops.These have been found to be no hindrance to taking the benefits of analmost quantitative division of the fat into substantially equal dropsof a size sufiiciently large for avoiding or minimizing undesirableemulsion formation and over-saponification and for ensuring a stay ofall the substantially equal drops in substantially equal contact withthe lye for a substantially equally long time and thereby achieve asubstantially uniform treatment of substantially all parts of the fatwith the lye.

I wish it to be observed that my invention solves the problem ofavoiding or minimizing loss of neutral fat by emulsion formation andover-saponification and generally over-treatment or under-treatment ofany considerable proportion of the fat with the lye in a mannerradically different from that aimed at in continuous centrifugalrefining which is the most advanced hitherto known and applied fatrefining process. In continuous centrifugal refining as Well as in allother known and applied industrial alkali wet refining of fat for edibleuse, the lye during its action on the fat is present in an amount thatis small as compared with the present amount of fat. In continuouscentrifugal refining, in which degumming, neutralizing and decolorizingoften are effected as a cornbined operation, one tries to minimizeover-saponification by using strong caustic soda lye for theneutralization and by shortening the reaction time (the duration of thecontact between lye and fat) as much as possible by vigorouslydispersing the lye in the fat, thereby promoting emulsion formation andusually necessitating an emulsion-breaking treatment of the mixture offat and lye before the separation of the neutralized fat from the spentlye (the soap-stock). When the neutralization operation is carried outin accordance with my invention, the dissolution of substances renderedwater-soluble or hydratable by the degumrning of the fat is enhanced andthe risk for over-saponification and emulsion formation is diminished byusing weak lye which during its action on the fat is present in anamount that is large as compared with the present amount of fat, and bysubjecting substantially all small separate and substantially equalparts into which the fat is dispersed in the lye to a substantiallyuniform action of the lye both as regards the contact between fat andlye and as regards the duration of this contact. This duration andthereby the degree of elimination of free fatty acids varies with theheight of the lye column, so that the required height of the lye columndepends upon the desired degree of elimination of free fatty acids. Therate of elimination of free fatty acids during the travel of the fatdrops up through the lye column decreases much more rapidly thanproportionally to the decrease of the free fatty acid content in thefat, and for this reason variations in height of the lye column causeonly relatively small variations in the degree of elimination of freefatty acids in the fat bubbled up through the lye column. By theguidance of general experience of fat refining, analyses of the fat andconventionally required laboratory tests for refining efficiency,skilled refiners will be able to choose a suitable initial strength ofthe lye and a suitable initial height of the lye column for achievingoptimum refining results with any given kind and quality of crude oil orother fat to be refined. When using caustic soda solution, an initialstrength thereof, expressed in normality, in the range about 0.3 toabout 1.5 and an initial height of about 2 rn. of the lye column havebeen found to be suitable for a thorough elimination of free fatty acidsin most oils and other fats used industrially for the manufacture ofsuch edible products as margarine.

In all refining of fats by means of alkali and thus also in my newmethod of carrying out the neutralization operation, the alkali must beused in excess over the amount theoretically required for saponificationof free fatty acids in the fat. Because alkali is consumed by thereactions taking place at the bubbling up of the fat through the lyecolumn, the lye must be renewed continuously or at intervals. Though itis possible to do this by discharging spent lye (soapstock) from theneutralizer and adding fresh lye or alkali without or only with shortinterruption of the feed of fat to the neutralizer, my preferred methodof renewing the lye is to change over the feed of fat to anotherneutralizer, charged in advance with fresh lye, when the alkaliconcentration of the lye in a neutralizer in operation has fallen to anormality, usually not lower than about 0.1, at which the lye has to beconsidered spent.

Within the purview of the principal objects and most important featuresof my invention, as described above in comparison with acknowledgedprior art, further objects and features of my invention will be apparentfrom the following description, with reference to the accompanyingdrawings, of forms of plant for carrying out my new fat refiningprocess.

In the drawings:

FIGS. 1, 2 and 3 are more or less diagrammatic views, each of onesection of a plant in which my new fat refining process can be carriedout,

FIGS. 4 and 5 are fragmental vertical sections on a larger scale, takensubstantially on line IVIV in FIG. 5 and on line VV in FIG. 4,respectively, of a modified form of the neutralizer;

FIG. 6 is a vertical section of a further modified form of theneutralizer,

FIG. 7 is a horizontal section substantially on line VIIVII in FIG. 6;

FIGS. 8 and 9 are fragmental vertical sections on a larger scale, takensubstantially on line VIIIVIII in FIG. 7 and on line IXIX in FIG. 8,respectively;

FEGS. 10, 11 and 12 show diagrammatically three variations of the plantshown in FIGS. 1 to 3 and exemplify how the plant and the operationthereof may be varied for treating ditferent oils requiring more or lessdifferent treatments for making them suitable for the manufacture ofedible products such as margarine.

FIGS. 1 to 3 illustrate the first plant built and put into use forpractising my invention on an industrial scale, the capacity of thisplant being about 2000 to about 3000 kg. of fat per hour, depending onthe nature of the fat.

As will appear from FIG. 1, the crude fat, which usually is a vegetableor animal oil, is taken into the plant in batches of a predeterminedweight, preferably about 500 kg., via an automatic weighing machine 1 tothe scalepan 2 of which the fat is supplied through a pipe 3. Theinterval of time between the batches is usually chosen in the rangeabout 10 to about 15 minutes. The pretreatment of the fat withphosphoric acid is carried out semicontinuously in a vertical container4, which is kept evacuated to an absolute pressure of preferably about20 mm. Hg through a pipe 5 which is connected to a vacuum pump. Disposedbeneath one another in the container 4 are four trays 6, 7, 8 and 9 ofacid-proof material. Each batch of fat is passed to the uppermost tray 6from the scalepan 2 through a pipe 10 and a spraying device 11 mountedabove the tray 6 for deaerating the fat. For heating the fat the tray 6contains a coiled pipe 12 which is heated by steam under the control ofa thermostatoperated valve. To attain a good heat transfer between thesteam-heated coil 12 and the fat in the tray 6, an agitator 13 isprovided. The three upper trays 6, 7 and 8 are provided with drains 14,15 and 16 provided with automatically controlled valves with largethroughflow area for rapid discharging of each batch of fat from theuppermost tray 6 to the next following tray 7, and later on from thistray 7 to the next following tray 8, and finally from this latter trayto the lowermost tray 9. Orthophosphoric acid of high concentration,preferably 85 percent by weight, is added to the fat in the tray 7 froma container 17 through a pipe 18 under the control of an automaticallyoperated dosage valve or pump 19. The tray 8 serves the purpose ofallowing the phosphoric acid to act upon the fat for a sutficiently longtime. The lowermost tray 9 serves as a buffer between the intermittentdischarge of the fat thereto from the tray 8 and a continuous pumping ofthe fat from the tray 9 by means of a pump 20. It may be suitable tocool the fat in the tray 9 more or less by means of a coiled pipe 21 forcooling water. Agitators 22, 23 and 24 are disposed also in the trays 7,8 and 9, and the agitators in all the trays are shown as driven by acommon motor 25. The valves in the drains 14, 15 and 16 from the trays6, 7 and 8, the phosphoric acid admixing valve 19, a valve 26 in the fatsupply pipe 3 and a valve 27 in the pipe can preferably be controlledfrom a common automatic program apparatus 28 in a system whichautomatizes the operation of the plant and which may be designedaccording to wellknown principles and therefore is but veryschematically indicated in the drawing. This system can be under thecontrol of say a pair of floats 29 and 30 in the buffer tray 9 so that anew batch of fat is admitted to the container 4 as soon as the fat inthe buffer tray 9 has sunk to a certain level, and so that the supply offat to the automatic weighing machine 1 is interrupted when the fat inthe tray 9 has risen to a certain higher level.

The pump 20, whose capacity corresponds to that of the plant, pumps thefat pre-treated with phosphoric acid through a pipe 31 to a filter 32(FIG. 2) which comprises a container in which a number of filter leavesof fine mesh wire net are inserted, through which the fat flow passes.At the start of the filtration a pre-coat of filter aid (purekieselguhr, for example) is deposited on the filter leaves. This iseffected as follows: in a container 34 connected to the pipe 31 througha float valve and a pipe 33 the filter aid is mixed with fat whereuponthe mixture is pumped through the filter 32 by means of a pump 35connected between the bottom of the container 34 and the pipe 33. At thestart of the filtration, the filter 32 and the container 34 are keptunder vacuum to avoid contact of the fat with air. The evacuation takesplace through a pipe 36 connected to the evacuated container 4. Untilall filter aid has been deposited in the filter leaves, fat is pumpedround from tray 9 through pipe 31, filter 32, pipe 37 and back to tray 9through a pipe 54 connected to pipe 37 through a relief pressure valve53.

After the filter aid has been deposited on the filter leaves in thefilter 32, the filtered fat is passed through the pipe 37 to theneutralizer which comprises a vertical tank 38 (FIG. 2) which is ofsquare cross-section and has a horizontal cross-sectional area of about2.25 sq. m. and a height of about 3.2 m. At some distance (about 7 cm.)over its funnel-shaped bottom, the tank is provided with a horizontalpartition or false bottom 39 dividing the interior of the tank into anupper compartment containing the lye column through which the fat isbubbled up and thereby neutralized, and a lower com partment receivingthe feed of filtered fat from the filter 32 through the pipe 37. From asmall distance (about 1 cm.) above the false bottom 39 the interior ofthe tank 38 is laterally divided on the greater part of its height intovertical cells by means of an insert con sisting of vertical partitions40 serving as turbulence dampeners in the lye column. The cells are ofsquare cross-section, and the side of the square is about 4 cm. Thefalse bottom 39 has a hole 41 with a diameter of about 2 mm. directlybeneath each of the vertical cells. Centrally the false bottom 39 isprovided with a tube 42 secured at its upper end in an opening in thefalse bottom 39 and projecting a distance toward the apex of thefunnel-shaped bottom of the tank which there has a drain 43 with adischarge valve through which the tank 38 can be emptied. Both the pipe37 from the filter 32 and a pipe 44 with connections for the supply oflye and water to the tank 38 are connected thereto beneath the falsebottom 39. At the upper end the tank 38 has a removable cover 45 with acentrally projecting neck por tion 46 from which at a distance from itsupper end there extends a pipe 47 having a valve 49 con-trolled by afloat 48 in the neck portion 46. The bottom and walls of the tank 38 areheat insulated.

At start of work, the tank 38 is first filled up to the neck portion 46with lye of suitable concentration by lye and water being suppliedthrough the pipe 44. Supply of fat through pipe 37 to the compartmentbeneath the perforated false bottom 39 in the tank 38 is then started.The amount of the lye being displaced by the fat is discharged from asuitable point of the tank 38 through a pipe 50 into a collectingcontainer :51 from which the displaced lye can be pumped back to thetank 38 through a pipe 52 by means of a pump connected therein. Forthorough elimination of free fatty acids in the fat, the lye column overthe false bottom 39 is adjusted to a height usually not less than about2 m. and not greater than about 2.5 m. The fat supplied through pipe 37forms a layer 74 beneath the false bottom 39 and penetrates from thislayer 74 upwards through the holes 41. Be neath the fat layer 74 underthe false bottom 39 there remains on the bottom of the tank 38 a layer75 of lye in direct communication with the lye column above the falsebottom 39 through the pipe 42 which -by-passes the fat layer 74 andkeeps filled with lye. The fat layers and lye layers in the tank 38 areindicated for greater clarity by different hatching, viz the fat byvertical and the lye by horizontal hatching. From the fat layer 74 underthe false bottom 39 the fat flows in substantially equal separatestreams up in the lye column above the false bottom 39 through the holes41 therein. Under substantially the sole action of their buoyancy in thelye, these fat streams project from the holes 41 like footstalkssubstantially vertically up in the lye column and keep on dividing attheir tops almost quantitatively into substantially equal separate dropsof a size usually regulated to about 1.5 mm. These drops travel inspaced relationship and each substantially its shortest way andconsequently with substantially the same rapidness up through the lyecolumn and collect on the surface thereof into a layer which rises upinto the neck portion 46 and is discharged therefrom through the pipe47. The pressure on the fat causing it to flow into the tank 38 isdelivered by the pump 20 and adjusted to and held constant at the valuerequired for obtaining the desired size, in most cases preferably about1.5 mm., of the substantially equal drops into which the fat dividesupon or rather soon after entering the lye column over the false bottom39 through the holes 41 therein. Said pressure, and with it the heightof the fat layer 74 beneath the false bottom 39, varies with the rate ofthe continuous supply of fat to said fat layer and remains constant whenthe supply of fat to said fat layer and the fiow of fat therefromthrough the holes 41 balance each other so that the height of the fatlayer 74 remains constant. Adjustment of the height of the fat layer 74beneath the false bottom 39 adjusts the rate of flow of 'the fat streamsfrom said layer up through the holes 41 and thereby the size of thedrops into which the fat streams soon divide in the lye column above thefalse bottom 39. It follows that the drop formation can be regulated byregulating the output of the pump 20. The drop formation is influencedby the diameter of the holes 41 which, however, must be sufiicientlylarge for not easily being clogged. For this and other practicalreasons, regulation of the drop size by regulation of the size of theholes 41, though at least theoretically possible, is preferably notresorted to.

The neutralized fat contains only so small residues of alkali and soapthat the conventionally required washing of the fat for removal of suchresidues preferably can be dispensed with. Therefore, the neutralizedfat is discharged from the tank 38 through pipe 47 with exclusion of airinto a container 57 at the top thereof through a spraying device 58. Thecontainer 57 is held evacuated (preferably to an absolute pressure ofabout mm. Hg) through an evacuating pipe 59 and is provided with a steamjacket 60 for heating the fat, usually to a temperature in the rangeabout 80 to about 90 C. In the container 57 citric acid, preferably inaqueous solution of a concentration of about 15 percent by weight, isadded to the fat from a container 61 through a dosage pump 62 in thesmall amount, usually less than 0.05 percent by weight of the fat,required for splitting the small soap residue in the fatinto free fattyacids dissolving in the fat and alkali, and for converting this andother alkali in the fat into alkali citrate. The container 57 at thesame time serves as a mixing container for the admixing of a filter aid(pure kiesel- 'guhr, for example) and is equipped with an agitator likethat in the mixing container 34. The fat is pumped from the container 57through a pipe 63 by means of a pump 64 to a filter 65 from which thefiltered fat is passed through a pipe 66 and a safety and rest filter 67to a storage tank or direct to deodorizing as desired. However, untilthe filter aid added in the container 57 has been deposited onto thefilter leaves in the filter 65 and a clear filtrate has been obtained,the fat is pumped by means of the pump 64 through a return pipe 68 backto the container 57 in which the fat level is held constant by a floatvalve 69 connected to the pressure side of the pump 64. This pump is ofovercapacity, and a pressure relief valve 70 inserted between thepressure and suction sides of the pump provides for the desirablelimitation of the pressure on the fat to the filter 65. Any excess ofcitric acid as well as the formed alkali citrate is precipitated insolid form in the fat by the vacuum drying thereof and therefore removedby the filtration of the fat through the filter 65.

For interrupting the operation of the plant and emptying it, say forcleaning the filters or for renewing the lye, the following procedure isadopted. As regards the section for the treatment of the fat withphosphoric acid, on interruption of the work the amount of fat remainingin the lowermost tray 9 is pumped round through the filter 32 back tothis tray until all of it has been filtered clear whereupon it is pumpedby a smaller pump 71 through a rest filter 72 into the tank 38. Thistank is emptied of fat, after the fat layer beneath the false bottom 3*)has disappeared up through the holes 41, by water being supplied to thelower part of the tank so that the layer of neutralized fat is displacedand driven over into the drying container 57. For emptying this lattercontainer and the filter 65 of the fat remaining therein, this fat restis pumped round through the filter 65 by means of the pump 64 untilfiltered clear and is then driven out through the rest and safety filter67 by means of a pump 73. Then the plant may have to be cleaned from oilrests therein. These untreated oil rests should be collected and theirweight subtracted from the weight of the weighed-in crude fat when it isdesired to make a true calculation of the achieved refining efliciencyexpressed as weighed-out refined fat in percentage of the weight ofneutral fat in weighed-in and treated crude fat.

One purpose of the design of the plant shown and described is to keepthe fat being treated out of contact with air at start and close of workas Well as during full operation of the plant.

FIGS. 4 and 5 illustrate modified and improved means for effecting thesubdivision of the feed of fat to the lye column in the thousands ofseparate substantially equal fat streams and for causing them to enterthe lye column under little, if any, other motive force than theirbuoyancy in the lye and in a fairly uniform distribution over the entirehorizontal cross-sectional area of the lye column. As

is apparent from FIGS. 4 and 5, the false bottom 39 is provided withholes 41 arranged in rows, and over each row of holes there is disposedon the false bottom 39 a fat distributing channel 76. On account of thefact that the fat in the lye tends to ascend and not to descend, thechannel 76 is inverted (turned with its bottom up) for really acting asa channel for the fat in the lye. The side walls of the channel 76 areapertured with the apertures 77 spaced apart by remaining teeth 78 ofsuch a shape that the apertures 77 between the teeth 78 extend up to theupturned bottom of the channel 76 and preferably decrease in width inthe upward direction. The fat flowing up through the holes 41 into eachchannel '76 distributes itself into a layer beneath the upturned bottomof the channel. From this layer substantially equal separate continuousstreams 79 of fat flow through the apertures 77 into the lye columnabove the false bottom 39. Because of flowing from the very beginningunder the action of nearly no other motive force than their buoyancy inthe lye, the streams 79 project like footstalks from the apertures 77substantially vertically up in the lye and soon divide at their topsalmost quantitatively into substantially equal drops which rise ininterspaced relation and each practically its shortest way up throughthe lye column to the surface thereof. This results in substantiallyequal duration of the stay of each of the substantially equal drops infull surface contact with the lye. It is a requisite, however, for theobtention of these results that turbulence in the lye column issuppressed by the turbulence dampeners 40 at least to the extentrequired for inhibiting such whirling, fluttering or flexing of the fatstreams 79 in the lye as would result in an irregular drop formation ofthe fat in the lye and possibly also in splitting or flowing together offormed drops by collisions between them.

FIGS. 6 to 9 illustrate a still further modified and improved form ofthe neutralizer. The tank 38 is of round cross-section and the bottom ofthe tank is preferably horizontal. The horizontal partition or falsebottom 39 which divides the interior of the tank into the uppercompartment for holding the lye column through which the fat is bubbledup, and a lower compartment to which the pre-treated (degummed) andfiltered fat is fed through the tube 37, consists of the upper end wallof a round and flat (disc-like) casing 80 which by means of short legsor distance pieces 81 rests on the bottom of the tank and which betweenits circumference and the cylindrical wall of the tank leaves a distanceto provide for an always open communication between the uppercompartment of the tank and the space between the casing 80 and thebottom of the tank. The casing 80 is provided with a twopart socket 82projecting radially out through an opening 111 the wall of the tank 38.The two parts of the socket 82 are attached to the wall of the tank andthereby to each other by means of flanges indicated at 83 in FIGS. 6 and7. In the socket 82 there is fitted a tube 84 which is connected to thepipe line 37 and for-ms an extension thereof and projects into thecasing 80 substantially diametrically thereof and is provided in itsupper side with a longitudinal slot 85 (FIG. 8) and is closed at itsfree end. The fat to be neutralized is fed to the casing 86 through thetube 84 and distributes itself through the slot 85 fairlv uniformly tothe layer 74 into which the fat spreads on the lye layer 75 whichextends up into the casing 80, as ind1cated in FIGS. 8 and 9. Outsidethe tank 38 the socket 8 2 has a depending pocket 86 (FIG. 6) providedwith a sight glass 87. A transparent tube 88 extends from the tube 84down into the pocket 86. At start of work with the tank 38 charged withfresh lye, the lye in tube 84 is expelled therefrom through tube 88 bythe fat supplied from pipe 37. During Work there is between fat and lyein the tube 88 a borderline observable through the sight glass 87. Fromthe bottom of the tank 38 there extends a draining pipe 89 with ashut-off valve 96), and from the bottom of the pocket 86 there extends aconduit 91 having a branch connected to the pipe 89 over a shut-offvalve 92, and a second brunch connected to a steam supply pipe 93 over ashut-off valve 94. During work the lye layer 75 is kept in lye-filledcommunication with the lye column above the casing 86 in the tank 38through the connections 89, 92, 91, 86, 82. The pipe 44 for the supplyof lye and water to the tank 38 is connected to the pipe 89 over ashut-off valve 95. Holes 41 in the false bottom 39 and fat distributingchannels 76 over the rows of holes 41 are arranged as in the 'form ofFIGS. 4 and with the exception that the upturned bottom of the channel76 over each row of holes 41 has a slight slope from a pointintermediate each two adjacent holes 41 toward each of the two holes, asis apparent from FIG. 8. This slight slope assists to distribute the fatuniformly to the distributor outlets 77. The turbulence dampeners 40 arearranged as described with reference to the form of neutralizer shown inFIG. 2 with the exception that the turbulence dampeners 40 extend onlyto about 20 cm. above the level at which the fat streams 79 enter thelye column through the fat distributor outlets 77. In the upper regionof the tank 38 and preferably clamped between the upper end of thecylindrical wall of the tank 38 and the removable cover 45 there is asubstantially horizontal foraminated partition 96 preferably consistingof a stainless steel wire net with a diameter of the wire of about 0.5mm. and with about to about 20, preferably about meshes per inch,through which the fat bubbled up through the lye column has to pass onits way up to the neck portion 46 from which it is withdrawn through thepipe 47 under the control of the float operated valve 49. The wire net96 has been found to enhance and speed up the rupture of any soap filmson the fat drops collecting on top of the lye column. The ruptured soapfilms separate from the fat drops and ink into the lye, and thecollecting fat drops flow together and form a homogeneous layer ofneutralized fat containing only very small residues of lye and soap.

The provision and arrangement of the casing 80, as shown and described,serves the purpose of making it possibl to clean the neutralizer, andespecially the means therein for the division of the fat feed into thethousands of separate substantially equal fat streams 79, by blowingwith steam which is supplied through the steam pipe 93 and conductedtherefrom through the conduit 91 and the socket 82 and the tubes 88 and84 into the casing 80, from which the steam has no other outlets thanthe holes 41 directing the steam up into the distributors 76.

With the use of very weak caustic alkali lye for the neutralization inthe neutralizer, it may happen that the fat after passing through thelye column does not separate satisfactorily from the lye. Any suchdifliculty can easily be overcome by increasing the ionic strength ofthe lye by neutral electrolytes (neutral salts), such as for exampleNaCl, KCl, NH CI, Na SO A small content, for example about 0.25 percentby weight, of such an electrolyte, preferably NaCl, in the lye issufficient for causing the fat to separate satisfactorily from the lye.

The size of the separate drops into which the fat streams 79 divide isinfluenced by the interface tension between fat and lye, which can bealtered in a favorable direction by a lowering of the surface tension ofthe lye. I have found that a lowering of the surface tension of the lyeby some suitable alkali resistant surface-active agent can be resortedto for expediting the obtention of the desired size of the fat drops.Several alkali resistant surface-active agents, also called wettingagents, are available 1 on the market for use as detergents, and amongthem a detergent consisting of a 60 percent by weight alkylarylsulfonatehas been found most suitable. A small content,

. for example about 0.25 percent by weight, of this detergent in the lyeis sufiicient for overcoming any difficulty to bring the fat streams 79to divide into not too small drops. This same expedient also appears tohave an improving effect on the drop formation as regards the uniformityof the substantially equal drops into which the fat streams 79 almostquantitatively divide.

In the variations of the refining plant schematically illustrated inFIGS. 10, 11 and 12 there are only three trays (6, 8 and 9) in thevacuum drying container 4 in which the pretreatment with phosphoric acidis performed, in that the phosphoric acid is added to and mixed with theoil in the uppermost tray 6 in which a cylindrical heating element 120is substituted for the coiled heating pipe 12 in FIG. 1. In all thethree variations illustrated in FIGS. 10, 11 and 12, the neutralizer 38is of the'construction shown in and described with reference to FIGS. 6to 9. For economical reasons a centrifugal clarificator (not shown) canbe connected in the pipe line 31 for separating off the greater part ofthe sludge in the pretreated oil before the filtration through thefilter 32.

In the variation of the plant illustrated in FIG. 11, there are providedin the vacuum drying container 57, in which the citric-acid treatmentfinishing the neutralization operation is performed, three superimposedtrays 97, 98, 99 of which the two uppermost have bottom outletsautomatically controlled by valves 100 and 101, respectively. The oil ispassed from the neutralizer 38 through the pipe 47 and the sprayingdevice 58 continuously to the upper- =most tray in which the oil istreated with citric acid continuously supplied through the dosage means61, 62. From the tray 97 the oil is passed batchwise to the tray 98 andtherefrom batchwise to the tray 99, from which the oil is pumpedcontinuously to and through the filter 65. Motordriven stirrers 103,like those in the trays in the vacuum drying container 4, are providedin the trays in the vacuum drying container 57. Dosage means 104 areprovided for adding filter aid and, if needed, bleaching earth to theoil in the intermediate tray 98.

The variation of the plant illustrated in FIG. 12 differs from thevariation illustrated in FIG. 11 by an additional tray 105 beingprovided between the trays 97 and 98 in the vacuum drying container 57.The oil is passed from this additional tray 105 to the tray 98 through acentrifugal separator 106 located outside the container 57. There arealso the further differences that the citric acid dosage means 61, 62are arranged to add the citric acid to the oil in the lowermost tray 99and that dosage means 107 are provided for adding a small amount of somereagent, preferably in aqueous solution, that is known or found tofurther the elimination of coloring matter and/or other undesirablesubstances such as oxidation products in the fat. Examples of suchreagents are sodium hydroxide and sodium carbonate. When using any ofthese reagents a small amount of precipitating soap is formed which instatu nascendi absorbs coloring matter and possibly also otherundesirable substances in the oil. The formed soap is separated from theoil in the centrifugal citric acid are added 61, 62 prior to the finalfiltration of the oil through the filter 65.

All directions concerning the construction and operation of the refiningplant given in the above description with reference to FIGS. 1 to 9 areapplicable also to the variations of the plant schematically illustratedin FIGS. 10, 11 and 12 as far as not altered by the above description ofthese variations.

In all refining of oils for edible purposes and thus also in therefining of oils by my new refining process, the refiner must vary thethoroughness of the various treatments, especially the pre-treatment(degumming) with the nature and quality of the crude oil to be refinedin order to obtain as good refining results as possible both from thepoint of view of cost and of refining efiiciency and purity and color ofthe oil when ready for edible use or for the manufacture of edibleproducts such as margarine. Only a rough grouping of the most commonoils that are refined industrially for edible purposes can be given Withrespect to how thoroughly they usually have to be treated for obtainingsatisfactory refining results by my new refining process, namely:

(i) Oils with a low content of lecithin and a low content of coloringmatter. Customarily coconut oils, palm kernel oils and hydrogenated oilsof good qualiites belong to this group. For the deg-umming of oils ofthis group by phosphoric acid, only a very small amount thereof isrequired, and there is no need for bleaching after the neutralizationoperation.

(ii) Oils with a high content of lecithin and a moderate content ofcoloring matter. Customarily soybean oils, rapeseed oils and pale palmoils of good qualities belong to this group. For the degumming of oilsof this group by phosphoric acid, the required amount thereof is greaterthan that required for oils of group (i). There is usually no need ofbleaching after the neutralization operation.

(iii) Oils with a high content of lecithin and a high content ofcoloring matter. Cottonseed oils and dark palm oils are examples of oilscustomarily belonging to this group. For the degumming of oils of thisgroup by phosphoric acid, the required amount thereof is still greaterthan that required for oils of group (ii), and after the neutralizationoperation bleaching by bleaching earth may be required and can beperformed by adding the bleaching earth to the oil in the finishing stepof the refining process, that is in the vacuum drying container 57 inwhich the oil is treated for a thorough elimination of soap residueprior to the final filtration prior to the deodorization.

For a full understanding of the further elucidation of the inventionbelow by examples of how and with what results my new refining processhas been adapted for the refining of various oils, there is first givenbelow an account of the methods used for determining the results. Thefollowing abbreviations are used: AOCS:Official and Tentative Methods ofthe American Oil Chemists Society, DGF=Einheitsmethoden der DeutschenGesellschaft fur Fettwissenschaft; lUPAC -lnternational Union of Pureand Applied Chemistry; FFA=free fatty acids.

Official Method Cd 325 as This method has been used for determining thecontent of neutral oil consisting essentially of triglycerides plusunsaponifiable fatty matter in the crude oil, FFA and nonfatty matter inthe oil being retained by the activated alumina column used in thistest. When the crude oil had a high content of lecithin the neutralizedoil was checked for residual phosphorus content which, if any, indicatedthat some lecithin had passed the alumina column. In all such cases thefigures have been corrected according to the result of this checking.

Moisture and volatile matter: AOCS Official Method Ca 2c25 as revisedApril 1956. This method determines the moisture and any other mattervolatile under the conditions of the test.

Insoluble impurities: Determination according to DGF- Method cur 11(53).The method determines dirt, meal and other foreign substances insolublein petroleum ether.

Soap content of refined oil: Method of Wolff: Journal of the AmericanOil Chemists Society 34, 293 (1957). Soap content expressed aspercentage of sodium soap by weight of the fat.

Lecithin and other phosphatides: AOCS Official Method Ca 12-55, countingpercentage of phosphatides by weight of the fat as equivalent to 30times the percentage of phosphorus by weight of the fat.

l 6 Color: AOCS Tentative Method CC 13C-50, determining the opticaldensity for yellow color at wave length 4600 A., for red color at wavelength 5500 A., and for green color at wave length 6700 A.

Notes: The iodine value is a measure of the unsaturation of a fat. Theiodine value and the saponification value are characteristic values bywhich a fat can be identified. Good correlation between these values forincoming and for outgoing oil indicates that no contamination of the oilhas occurred in the refining process. The peroxide value and thebenzidine value each and together give an indication of the oxidativestatus of the oil. As peroxides and carbonyl compounds constitute theprecursors of bad-tasting decomposition products, it is in the interestof the refiner that the peroxide and benzidine values are low from thebeginning and are decreased in the refining process or at least kept aslow as possible.

Example 1.Refining of a crude coconut oil A feeding tank for therefining plant was charged with 15,0865 kg. of a crude coconut oil.Analyses of the crude oil showed:

Free fatty acid "percent" 3.94 Iodine value 8.7 Saponification value 256Peroxide value 0.0 Benzidine value 2.8 Neutral oil percent 95.29Moisture do 0.08 Insoluble impurities do 0.02

The oil was preheated in a heat exchanger and passed in batches, eachamounting to about 500 kg, at the frequency of one batch every 15minutes, to the phosphoric acid treatment unit (the vacuum dryingcontainer 4) of the plant and there deaerated, vacuum dried and heatedto 75 C. The vacuum in the container 4 was kept at 20 mm. Hg absolutepressure. To each batch of oil there was added about 0.04 percent byweight of phosphoric acid of a concentration of percent by weight. Atotal of 6.5 kg. of phosphoric acid was added to the total of oil. Afterthe prolonged reaction time in the trays in the container 4, thephosphoric-acid-treated oil was pumped continuously from the lowermosttray 9 to and through the filter 32 which was given a precoat with inall 14 kg. of a filter aid known under the trademark Hyfio, which is apurified kieselguhr (diato-rnaceous earth). After the filtration of allthe oil 36 kg. of filter cake Were collected, which contained, inaddition to the spent filter aid, impurities, phosphoric acid and someretained oil.

After the filtration the filtered oil was passed to the neutralizer (thecontainer 38) which was charged in advance with 4,700 liters of a lyecontaining per liter 32 gr. of sodium hydroxide dissolved indemineralized city water. The horizontal cross sectional area of the lyecolumn through which the oil was bubbled up in the neutralizer was 2.25sq. m. The temperature of the lye was kept at 72 C. Analyses of theneutralized oil showed:

Percent Free fatty acid 0.04 Moisture 0.11 Soap Traces The neutralizedoil was passed to the citric acid treatment unit (the vacuum dryingcontainer 57), of the refining plant and there heated to C. and vacuumdried at 20 mm. Hg absolute pressure and treated with about 0.01 percentby weight of citric acid which was added in aqueous solution of aconcentration of 15 percent by weight. The oil was then pumped throughthe filter 65 which was given a precoat with in all 4 kg. of the filteraid Hyflo. The weight of collected filter cake was kg. Analyses of thecitric-acid-treated and filtered oil showed:

Free fatty acid percent 0.04 Iodine value 8.7 Peroxide value 0.0Benzidine value 0.8

Moisture percent 0.01 Insoluble impurities do 0.01

Percent Free fatty acid 94 Moisture 1.2 Insoluble impurities 0.02

Example 2.Refining of a crude hydrogenated whale oil A feeding tank forthe refining plant was charged with 49,2315 kg. of a crude hydrogenatedwhale oil. Analyses of the crude oil showed:

Free fatty acid percent 0.29 Iodine value 52 Saponification value 189Peroxide value 1.1 Benzidine value 2.3 Neutral oil percent 99.44Moisture do 0.02 Insoluble impurities do 0.01

From the feeding tank the oil was passed in batches, each amounting toabout 500 kg., at the frequency of one batch every minutes, to thephosphoric acid treatment unit of the refining plant through a heatexchanger in which the oil was preheated to about 75 C. before it wasintroduced into the vacuum drying container 4. In the first tray 6 inthe container 4, the oil was deaerated and vacuum-dried and thetemperature adjusted to 80 C. The vacuum in the container 4 was kept atmm. Hg absolute pressure. To each batch of oil there was added about0.03 percent by weight of phosphoric acid of a concentration of 85percent by weight. The total amount of phosphoric acid added to thetotal amount of oil was 15.8 kg. After the prolonged reaction time inthe trays the oil was pumped continuously from the lowermost tray 9 andthrough the filter 32, which was given a precoat and during theoperation two further coats with in all 39.3 kg. of kieselguhr (Hyflo).After the oil in the feeding tank had been worked up and the filterleaves had been sucked, 82.2 kg. of filter'cake could be collected whichcontained, in addition to the spent filter aid, impurities, phosphoricacid and some retained oil.

The neutralizer (the container 38) was charged in advance with 4,700liters of a lye containing 12.0 gr. of sodium hydroxide per liter, 0.25percent of a 60 percent alkylaryl-sulfonate (surface tension loweringagent), and 0.25 percent of sodium chloride (neutral additional electrolyte), all dissolved in demineralized city water. The horizontalcross-sectional area of the lye column through which thephosphoric-acid-treated and filtered oil was bubbled up was 2.25 sq. m.The temperature at which the neutralization was carried out was 85 C.Analyses of the neutralized oil showed:

The neutralized oil was continuously withdrawn from the neutralizer (thecontainer 38) to the citric acid treatment unit (the vacuum dryingcontainer 57) of the plant, in which the oil was heated to C. and vacuumdried and treated with about 0.01 percent by weight of citric acid whichwas added continuously in aqueous solution of a concentration of 15percent by weight. The citricacid-treated and vacuum dried oil waspumped through the filter 65 which was given a precoat of kieselguhr(Hyflo). The total amount of kieselguhr usedwas 9 kg., and the weight ofcollected filter cake was 46.4 kg.

Analyses of the citric-acid-treated and filtered oil showed:

Free fatty acid percent 0.03 Iodine value 52 Saponification value 189Peroxide 0.5 Benzidine value 1.8 Moisture percent 0.02

Insoluble impurities do 0.01

On cleaning the feeding tank and the refining plant from all rests ofoil after close of work, 166.8 kg. of oil could be collected. The totalyield of neutralized oil was 48,800 kg.

The soapstock was acidulated with sulfuric acid to recover the fattyacids. The recovered fatty acids had a dry weight of 147 kg. Analyses ofthe acid oil showed:

Percent Free fatty acid 98 Moisture 1.3 Insoluble impurities 0.02Mineral acid Traces Example 3.Refinz'ng of a crude rapeseed oil Afeeding tank for the refining plant was charged With 11,183 kg. of acrude rapeseed oil. Analyses of the crude oil showed:

From the feeding tank the -oil was passed through and preheated in aheat exchanger and then to the phosphoric acid treatment unit of therefining plant in batches and deaerated and vacuum dried as in Examples1 and 2 and heated to 85 C. and treated with about 0.4 percent. byweight of an 85 percent phosphoric acid. After the prolonged reactiontime in the trays in the vacuum drying container 4, the oil was pumpedcontinuously from the lowermost tray in this container to and through afilter having a filter area of 6 sq. m. which was given a precoat ofkieselguhr (Hyflo) and further coats of this filter aid in the course ofthe work. For the total of oil a total of 45.6 kg. of phosphoric acidand a total of 28.9 kg. of kieselguhr were used. After finishing theoperation and sucking the filter leaves 80.0 kg. of filter cakes werecollected which contained, in addition to the spent filter aid,impurities, phosphoric acid and some retained oil. In the pipe linesthrough which the pretreated and filtered oil was pumped to theneutralizer there were connected a mixer with a rotating stirrer drivenat a moderate speed. In this mixer about 3 percent by volume ofdemineralized city water was continuously mixed with the oil. Thismodification of the process led to a slightly better yield of neutraloil. The neutralizer had been charged in advance with 4700 liters of alye containing 12 gr. of sodium hydroxide per liter and 0.25 percent byvolume of a 60 percent alkylarylsul-fonate and 0.25 percent by weight ofsodium chloride, all dissolved in demineralized city water.

The temperature of the lye was 85 C., and the horizontal cross-sectionalarea of the lye column through which the oil was bubbled up was 2.25 sq.m. Analyses of the neutralized oil showed:

From the neutralizer the neutralized oil was continuously withdrawn to avacuum drying unit (container 57) similar to that shown in FIG. 12. Inthis unit the temperature was adjusted to about 85 C., and in the firsttray (97) sodium carbonate in an amount of about 0.04 per weight of theoil was added in the form of an aqueous solution containing 212 gr. NaCO per liter. After about 15 mintues reaction time in the second tray(105), a small amount of kieselguhr (Hyflo) was added in the third tray(98). Finally, the oil was continuously passed through a filter (65)with a filter area of 6 sq. m. For the total of the oil a total of 13kg. of kieselguhr was used, and after finished operation 34.4 kg. offilter cake were collected. Analyses of the refined oil after the finalfiltration showed:

Free fatty acid percent 0.04 Iodine value 103 Saponification value 174Peroxide value 1.7 Benzidine value 2.0 Moisture percent (0.02 Insolubleimpurities d 0.01

On draining of the plant from all oil rests, 169 kg. of oil could becollected and deducted from the input of crude oil. The weight of thedry refined oil was 10,670 kg.

The soapstock was acidulated and analyses of the acid oil showed:

Percent Free fatty acid 94 Moisture 1.0 Insoluble impurities 0.01Mineral acid Traces The dry weight of recovered fatty acids was 307 kg.

Example 4.Refining of a crude soybean oil A feeding tank for therefining plant was charged with 12,481 kg. of a crude soybean oil.Analyses of the crude oil showed:

The crude oil was preheated in a heat exchanger and passed in batches tothe first tray of the phosphoric acid treatment unit and deaerated,heated to 85 C., and vacuurn dried, as in the preceding examples. Insaid first tray, about 0.16 percent by weight of phosphoric acid of aconcentration of 85 percent by weight was added to each batch of oil. Atotal of 19.8 kg. of phosphoric acid was added to the total oil. Afterthe prolonged reaction time in the trays, the oil was continuouslypumped to and through a filter with a filter area of 6 sq. m. which wasgiven a precoat and in the course of the work further coats of in all14.3 kg. of kieselguhr (Hyflo). After finishing the operation andsucking the filter leaves, 61.5 kg. of filter cake could be collectedwhich contained, in :addition to the spent filter aid, impurities,phosphoric acid and some retained oil.

The pretreated and filtered oil was continuously fed to the neutralizerwhich was charged in advance with 4700 liters of a lye containing 12 gr.of sodium hydroxide per liter, 0.25 percent byweight of sodium chlorideand 0.25 percent by volume of a 60 percent alkylarylsulfonate, alldissolved in demineralized city water. The horizontal cross sectionalarea of the lye column was 2.25 sq.m., and the temperature of the lyewas 85 C. Analyses of the neutralized oil bubbled up through the lyecolumn in the neutralizer showed:

Percent Free fatty acid 0.14 Moisture 0.10 Soap Traces Free fatty acidpercent 0.05 Iodine value 132 SapOnification value 193 Peroxide value0.8 Benzidine value 2.6 Moisture percent 0.02

On draining the plant from all oil rests, 52.5 kg. of oil could becollected and deducted from the input of crude oil. The yield ofneutralized oil was 12,264 kg. (dry weight).

Analyses of the acid oil obtained by acidulating the soapstock showed:

Percent Free fatty acid 93 Moisture 1 Impurities 0.05 Mineral acidTraces The dry weight of recovered fatty acids was 113 kg.

Example 5.Refining of a crude palm oil A feeding tank for the refiningplant was charged with 12,5494 kg. of a crude palm oil. Analyses of thecrude oil showed:

Free fatty acid percent 5.08 Iodine value 56 Saponification value m. 198Peroxide value 3.4 Benzidine value 18.7 Neutral oil percent 94.15Moisture do 0.09 Insoluble impurities do 0.05

After having been preheated to about C. in a heat exchanger, the crudeoil was passed to the first tray of the phosphoric acid treatment unitof the plant in batches and deaerated and vacuum dried, as in thepreceding examples. The temperature was adjusted to C. In the said firsttray, 0.1 percent by weight of phosphoric acid of a concentration of 85percent by weight was added to each batch of oil. To the total of oil atotal of 14.7 kg. of phosphoric acid was added. After the prolongedreaction time in the trays, the oil was pumped continuously through afilter with a filter area of 6 sq. m., which was given a precoat and inthe course of the work further coats with in all 19.9 kg. of kieselguhr(Hyflo). After finishing the operation and sucking the filter leaves,63.2 kg. of filter cake could be collected which contained, in additionto the spent filter aid. impurities, phosphoric acid and some retainedoil.

